DE202013101174U1 - Plant for processing biomass, preferably a plant for the production of paper, pellets or material plates - Google Patents

Abstract

Plant for processing biomass, comprising a dryer (13) for drying the biomass (B) to form dried biomass (BT), a chimney (15) for releasing the exhaust air (A) from the dryer (13) to the environment and at least part of it the system for processing the dried biomass (BT), preferably a processing system (14) for the production of paper, pellets or material panels, characterized in that a spray tower (2) in the system between the dryer (13) and the chimney (15) is arranged for spraying at least one moisture-containing partial flow of the exhaust air (A) with water (W), which is suitable for collecting the condensate (K) resulting from the accompanying cooling of the exhaust air (A) and means are provided in the system that from the condensate (K) resulting waste water (AW) at least parts of the system for humidification and / or temperature control of the biomass (B) to be fed.

Description

The present invention relates to a plant for processing biomass, preferably a plant for the production of paper, pellets or material plates, according to the preamble of claim 1.

Systems and the essential physical processes in these systems are already known from the prior art. DE 35 34 260 A1 discloses a method for thermally drying temperature-sensitive goods in rotary drums, in particular biomass. It is described that for drying usually high-temperature flue gases are used directly or indirectly to dry the goods. In particular, the recirculation of the vapors (exhaust air) of the dryer for reuse as mixed air for controlling the flue gases is proposed in order to avoid heat losses. However, the majority of the wet vapors are still released to the environment, as usually not so much vapor can be used as mixed air in connection with the combustion, to ensure a complete cycle. Also, the vapors are already burdened with moisture and from too high a humidity, the mixed flue gases would not be suitable for direct drying to absorb moisture from the material.

Out DE 42 17 116 A1 a general method has been known for the purification of air, enriched with the exhaust air or exhaust gas with water vapor and then cooled below the current dew point for the liquid in question. It forms a mist, which absorbs the air polluting substances and can be separated.

Essentially, these physical processes also use a wet electrostatic precipitator, in which the exhaust air of a dryer is sprayed with water and thus saturated. The saturated exhaust air is finally ionized and dust and aerosols are deposited on the electrodes, which in turn are cleaned by means of water spraying. This wastewater is regenerated and usually used again for the water spray in the wet electrostatic precipitator, yet a large part of the water escapes through the saturation of the water in the exhaust air through a fireplace. In principle, wet electrostatic precipitators are operated in such a way that the amount of wastewater discharged remains as low as possible.

Basically, it is therefore known to expose exhaust gases in industrial application of a targeted saturation in a spray tower, the skilled person knows it but usually deliberately to avoid unnecessarily produce wastewater that will be regenerated and purified. For this purpose, the exhaust air is usually saturated only in such a way that when cooling, although a certain condensation effect occurs, but this should be kept as low as possible, cf. For this purpose, the above-described application of wet electrostatic precipitators.

Such systems, however, always have a generous use of fresh water in the individual parts of the system and of course in the spray tower, since the moisture is absorbed by the exhaust air and can be discharged in gaseous form via a chimney. In the interests of environmental protection, it is only necessary to clean the exhaust air in such a way that it contains no or only a small amount of pollutants. The moisture content of the exhaust air is usually taken into account only if misting and rain in the immediate vicinity is to be avoided, especially in cold seasons.

Out DE 601 02 915 T2 For example, a method and apparatus for defrosting tree trunks by means of hot water or steam has become known. Such methods or equipment may be used in the present process under circumstances where the biomass should be in the form of tree trunks. For this purpose, however, it is necessary to produce hot water or steam by means of expensive primary energy (gas, oil, coal, wood ...) and to sprinkle or apply the tree trunks with the heated medium. Again, it is necessary to use a lot of fresh water, which must be processed to hot water or steam.

In conventional systems, therefore, generalized biomass is processed by drying the biomass in a dryer to dried biomass, the discharge of the exhaust air of the dryer in a fireplace to the environment and the processing of the dried biomass in a part of the plant, preferably in a processing plant for Production of paper, pellets or material plates happens.

The present invention therefore has the technical object to provide a system in which the use of fresh water over the prior art can be saved and / or in which the efficiency of the entire system can be increased by reusing the low calorific energy.

The solution for the system is that in the system between the dryer and the fireplace, a spray tower for spraying at least one moisture-containing partial flow of the exhaust air is arranged with water, which is suitable to collect the condensate resulting from the associated cooling of the exhaust and wherein means are provided in the system, which consists of Condensate produced waste water at least parts of the system for humidification and / or temperature control of the biomass.

Essentially, the exhaust air is supersaturated with moisture by the humidity of the exhaust air is enriched until the exhaust air can no longer absorb moisture. Due to the parallel cooling, the moisture and the heat contained in the air are removed via the condensate of the exhaust air and stored in the resulting wastewater. The exhaust air cools accordingly, the condensing moisture and also the exhaust air flowing through the water takes on a higher temperature.

This results in a high-temperature wastewater, which can be used directly for heating or for thawing the biomass, which can lead to an indirect or direct heating depending on the application. In the case of direct heating, the wastewater is brought back into direct contact with the biomass (for example tree trunks). When contacting takes place but usually not only a warming, but water is also absorbed by the biomass in this case, then dried out of the biomass in the dryer and transferred to the exhaust air, there again condensed out of the exhaust air in the spray tower and thus be reused. This results in a nearly closed circulation of water. In any case, it is thus achieved that the fresh water consumption of comparable processes or plants is significantly reduced and quasi-low-calorie energy can be usefully used in a meaningful way.

• – die Einsparung von Frischwasser;
• – die zumindest anteilige Wiederverwendung von Wasser in einem Kreislauf;
• – die Verwendung niederkalorischer Energie der Abgase zur Erhöhung der Energieeffizienz der Gesamtanlage;
• – die einfache und energetisch kostengünstigere Luftreinigung der Abgase gegenüber einer regenerativen thermischen Oxidation (RTO) oder einem Nasselektrofilter, oder falls diese dennoch notwendig ist zumindest eine erste Vor- oder Teilreinigung der Abgase.

Thus, the advantages of the invention essentially comprise individually and above all in combination:

• - the saving of fresh water;
• - the at least partial reuse of water in a cycle;
• - the use of low calorific energy of the exhaust gases to increase the energy efficiency of the whole plant;
• - The simple and energetically cheaper air purification of the exhaust gases compared to a regenerative thermal oxidation (RTO) or a wet electrostatic precipitator, or if this is still necessary at least a first pre- or partial cleaning of the exhaust gases.

Particularly noteworthy is now the fact that compared to the previous practice of heating fresh water for thawing or tempering the biomass and use, now accumulating wastewater can be meaningfully used. In particular, the fact is taken into account that hitherto fresh water has been used in spraying the biomass, which was taken in the course of the temperature control by the biomass, then discharged in the dryer of the dryer exhaust air and then to the environment. This water is now essentially circulated and reused, which significantly reduces the fresh water requirement of the entire system. By using the low calorie energy, there is even an energetic advantage that further significantly improves the overall economy of the plant.

Advantageously, the system of the invention also has advantages in a possible connection of a wet electrostatic precipitator, since this almost no fresh water supply needed because the exhaust air is here already saturated to the necessary content and it can be passed directly to the ionization to further pollutants from the exhaust air to remove.

In essence, it is therefore conceivable that the temperature or the humidification by means of the resulting wastewater in all parts of the system could find direct or indirect, complete or supportive, use. It would be conceivable to use the wastewater for the production of steam for the steaming of the comminuted wood before pelleting or pressing. Also, an admixture of the waste water in the glue liquor, with a possible corresponding heating of the glue liquor is conceivable. Necessary cleaning measures of the waste water will be considered by the skilled person with appropriate use, if advised. For example, the water can be sprayed substantially unrefined directly on tree trunks for heating, whereas the use of the wastewater, for example, in a glue liquor or as a vaporization a corresponding pre-cleaning or pH adjustment may be necessary.

In a preferred embodiment, the waste water for humidification and / or temperature control of the biomass can thus be used in the system parts upstream of the dryer.

To save or reuse drying energy, the temperature level of the biomass can be increased directly or indirectly before drying in the dryer by means of the wastewater. Preferably, the biomass can thus be thawed before comminution and / or before drying. This would be necessary, for example, especially in winter or also useful for plants that are provided in cold areas with regular frost.

Preferably, the biomass before and / or after drying in the dryer in a Device, preferably in a hacker and / or in a mill, be crushed and, if necessary, before and / or after moistened and / or tempered. This may be particularly useful when using biomass from logs or from a re-use.

In one possible embodiment, the exhaust air between the dryer and the spray tower and / or between the spray tower and the chimney in a cleaning device can be cleaned, preferably by means of a wet electrostatic precipitator and / or a regenerative thermal afterburning.

In one possible embodiment, for discharging the exhaust air from the chimney, a partial flow of hot exhaust air can be branched off before the spray tower or fed from another source and mixed after the spray tower with the cooler exhaust air from the spray tower. Such is the temperature of the exhaust air and thus the absorption capacity of the exhaust air is increased again, which reduces the relative humidity within the exhaust air and helps prevent the formation of steam outside the fireplace with appropriate cooling to the ambient air.

In particular, it can also be provided to use the wastewater for heating at least parts of the plant or indirectly for feeding into a district heating system.

From an installation point of view it can be provided that atomizers or steam generators and / or indirect use of heat exchangers are arranged for direct use of the waste water.

In particular, it can be provided that the spray tower for the use of the waste water for humidification and / or temperature control of the biomass with the dryer upstream equipment parts is operatively connected by means of lines. Lines are in the context of the invention suitable piping with corresponding drive means (pumps), which are suitable to lead the necessary fluids (water, sewage, fresh water, condensate, etc.) to their destination. Lines can also be arranged for air guidance, such as, inter alia, for the flue gases or exhaust air.

In particular, it can be provided that the plant further comprises a comminution device, preferably a chipper and / or a mill, for comminuting the biomass before and / or after drying in the dryer.

In a further additional embodiment may be arranged in the system for cleaning the exhaust air between the dryer and the spray tower and / or between the spray tower and the chimney, a cleaning device, preferably a wet electrostatic precipitator and / or a regenerative thermal afterburning.

In a further additional embodiment may be arranged for the discharge of the exhaust air from the chimney lines for the separation of a partial flow of hot exhaust air in front of the spray tower, which are operatively connected to the lines of cooler exhaust air from the spray tower to the mixture.

In a further preferred embodiment, means for using the waste water for heating at least parts of the plant or for indirect feed can be arranged in a district heating system.

The process and the plant can be operated independently of each other; but the system may also be suitable in particular for carrying out the method.

Further advantageous measures and embodiments of the subject matter of the invention will become apparent from the dependent claims and the following description with the drawing. The combination options shown in the figure description are all individually and independently and in any combination usable. In particular, individual sentences should also be evaluated as independent characteristics, similar to new paragraphs.

Show it:

1 a schematic representation of a plant according to the prior art,

2 a simplified schematic representation of a system according to the invention and

3 a more comprehensive presentation 2 ,

1 shows a schematic representation of a plant 1 according to the state of the art for processing biomass to an unspecified end product. This end product may preferably be paper, pellets, in particular for combustion in hearths or else a material plate. In the present example is an attachment 1 presented for the production of material plates in which a storage bin 17 for storage of logs 7 (as biomass B) and in the direction of production below a tempering device 4 is arranged. In the tempering device 4 may preferably be optionally by means of a water bath and / or a sprinkler 9 the tree trunks 7 tempered, so preferably warmed up or even thawed. This is usually an energy system 11 provided that over a Thermal oil supply 20 and a suitable heat exchanger 10 the water bath and / or a water circuit for the sprinkler 9 supplied with heat energy. The water cycle has an inlet for fresh water FW, which substitutes the water leaving the circuit, which either evaporates or from the logs 7 is recorded. The logs 7 are then in a crushing device, here as a hacker 16 registered, crushed and as wood chips 8th via an entrance lock 12 the dryer 13 supplied for drying. The entrance lock 12 , respectively the dryer 13 , is directly by means of a burner (not shown) or indirectly via the energy system 11 supplied with flue gas RG of a high temperature to allow the wood chips 8th to dry. In a dryer 13 downstream exit lock 18 become the wood chips 8th separated from the flue gases RG, the wood chips 8th as BT dry biomass in a processing plant 14 , usually via a thermal oil supply 19 with the energy system 11 operatively connected, further processed. The exhaust air A from the dryer 13 That removes the moisture from the drying process from the dryer 13 has a fireplace 15 fed to the ambient air, taking in front of the fireplace 15 another cleaning device 21 For example, a wet electrostatic filter or the like may be arranged.

Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS 2 and 3 explained in detail.

In a simplified representation of 2 The treatment of biomass by two possible ways (also combinatorially applicable as 1 ) on Temperierungsvorrichtungen 4 shown, after which the biomass B in the dryer 13 and as dry biomass BT in a processing plant 14 is further processed. According to the invention at least part of the exhaust air A from the dryer 13 in a spray tower 2 introduced, in which the rising exhaust air A by means of a nebulizer 3 with water W is applied. By cooling the exhaust air A and the direct condensation condensate K, which emerges as waste water AW from the spray tower 2 can be discharged. It is now intended, this wastewater AW indirectly via a heat exchanger 10 for heating the tempering device 4 to use, which is exemplified here as a water bath bottom left. Alternatively or in combination, the wastewater AW can also be used directly in a tempering device 4 to the biomass B by means of a sprinkler 9 be applied. The recovered water W is cooled down again according to the atomizer 3 of the spray tower 2 fed. Again, the direct use of water W would be possible in a water bath.

In a more detailed representation, essentially consisting of the representation after 2 , the missing details are taken out 1 exemplary in a plant 1 added after the invention, so that now a storage space 17 results from the wood logs to be tempered 7 in a tempering device 4 be introduced and there in a water bath and / or by means of a sprinkler 9 tempered, preferably thawed. The necessary water is used as wastewater AW from the spray tower 2 promoted. The returned water W is then back in the spray tower 2 by means of an atomizer 3 used against the exhaust air A to cool the exhaust air A and condense the moisture from the exhaust air A (direct condensation). The exhaust air A is after the spray tower 2 preferably in a cleaning device 21 , For example, a wet electrostatic precipitator or an RTO, finally cleaned and then on the chimney 15 delivered to the environment. In order to avoid that the very humid air (supersaturated from the direct condensation) in the lines from the spray tower or in the ambient air condenses excessively, it would be possible a part of the exhaust air A in front of the spray tower 2 branch off and after the spray tower 2 again to unite with the remaining exhaust air A. Due to the self-adjusting significant increase in temperature, the relative humidity in the exhaust air A lowers before the cleaning device 21 or the fireplace 15 clear. In an alternative, but in particular in a preferred additive embodiment, the effluent AW arising from the condensate K can be used for the support of further consumers or the heating of plant parts or halls of the plant and this is done via a heat exchanger 10 to absorb the low calorie energies by suitable consumers, here the processing plant 14 or another tempering device 4 ' in front of the dryer 13 directed.

LIST OF REFERENCE NUMBERS

1

investment

2

spray tower

3

atomizer

4

tempering

5

6

7

Log

8th

wood chips

9

sprinkling device

10

 heat exchangers

11

 power plant

12

 entry lock

13

 dryer

14

 processing plant

15

 fireplace

16

 hacker

17

 campsite

18

 exit lock

19

Thermal oil supply for 14

20

Thermal oil supply for 10

21

 cleaning device

B

biomass

BT

dry biomass

RG

fumes

A

exhaust

FW

fresh water

W

water

K

condensate

AW

sewage

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3534260 A1 [0002]
• DE 4217116 A1 [0003]
• DE 60102915 T2 [0007]

Claims (7)

Plant for processing biomass, comprising a dryer ( 13 ) for drying the biomass (B) to dried biomass (BT), a chimney ( 15 ) for discharging the exhaust air (A) of the dryer ( 13 ) to the environment and at least part of the plant for processing the dried biomass (BT), preferably a processing plant ( 14 ) for the production of paper, pellets or material plates, characterized in that in the plant between the dryer ( 13 ) and the fireplace ( 15 ) a spray tower ( 2 ) is arranged for spraying at least one moisture-containing substream of the exhaust air (A) with water (W), which is suitable for collecting the condensate (K) produced by the accompanying cooling of the exhaust air (A) and wherein means are provided in the system, the effluent (AW) produced from the condensate (K) at least parts of the system for humidification and / or temperature control of the biomass (B) supply. Installation according to claim 1, characterized in that for the direct use of the waste water (AW) atomizer ( 3 ) or steam generators and / or for indirect use of heat exchangers ( 10 ) are arranged. Installation according to claim 1 or 2, characterized in that the spray tower ( 2 ) for using the waste water (AW) for moistening and / or tempering the biomass (B) with the dryer ( 13 ) upstream equipment parts is operatively connected by means of cables. Installation according to one or more of the preceding claims, characterized in that the plant further for comminuting the biomass (B) before and / or after drying in the dryer ( 13 ) at least one comminution device, preferably a hacker ( 16 ) and / or a mill. Installation according to one or more of the preceding claims, characterized in that for cleaning the exhaust air (A) between dryer ( 13 ) and the spray tower ( 2 ) and / or between the spray tower ( 2 ) and the fireplace ( 15 ) a cleaning device ( 21 ), preferably a wet electrostatic precipitator and / or a regenerative thermal afterburning. Installation according to one or more of the preceding claims, characterized in that for the discharge of the exhaust air (A) from the chimney ( 15 ) Lines for separating a partial flow of hot exhaust air (A) in front of the spray tower ( 2 ) arranged with the lines of cooler exhaust air (A) from the spray tower ( 2 ) are operatively connected to the mixture. Plant according to one or more of the preceding claims, characterized in that means for using the wastewater (AW) for heating at least parts of the plant or for indirect feed are arranged in a district heating system.

Images